The invention relates to a process and a device for separating off one component from a gas mixture and to a process for recycling a gas mixture such as an anesthetic gas. The invention finds application, in particular, in connection with instruments for and techniques of xenon anesthesia.
The anesthetic effects of xenon have been known since the 1940s. A mixture of about 80% xenon and 20% oxygen is regarded as a virtually ideal anesthetic gas, with numerous advantages over the anesthetic gases predominantly in use today which are based on laughing gas. Owing to the high costs of xenon, xenon anesthesia is practiced hardly at all in the clinical field. In order to reduce these costs proposals have therefore been made, for example in DE 44 11 533 C1, for anesthetic machines having a xenon recovery system. In the case of the recovery system proposed in DE 44 11 533 C1, the exhaled respiratory gas is first cleaned and then compressed and passed into a pressure vessel which is taken into a cooling device. By means of the cooling device the pressure vessel is cooled to such an extent that the xenon that is to be recovered is liquefied. The gaseous constituents in the pressure vessel are let off through an outflow valve. When there is a sufficient amount of liquid xenon in the pressure vessel, it is pumped into a further vessel.
This device has the disadvantage of a highly complex apparatus for compressing the gas and for the cooling of an entire vessel. Moreover, the degree of transfer in xenon recovery is not satisfactory.
DE 35 18 283 A1 discloses a process for removing volatile purities from gases which are produced in the semiconductor industry, where the gas to be cleaned is guided, in a vacuum system, onto a cold surface of a condensor, on which condenser the gas to be purified is deposited while the more volatile impurities are drawn off continuously in gas form from the vacuum system. In this process too, the vacuum system used means that the apparatus for recovery is highly complex.